A drive control system of a stepping motor controls drive frequency of the stepping motor based on a measurement value inputted in a certain period. The stepping motor may generate vibration due to a resonance characteristic (drive frequency versus vibration acceleration characteristic) inherent in the stepping motor, and the vibration is transferred to a component being driven by the stepping motor, inducing resonance of the component, and consequently noise has been a problem. A system is given for solving the problem, which detects vibration of the component, and changes frequency depending on the detected vibration so as to prevent the resonance and the noise (for example, referring to patent document 1).
However, such a prior drive control system of a stepping motor has a problem that the detection means of detecting vibration of the component is necessary, leading to increase in number of components, and increase in cost associated with such increase in number of components. Therefore, a system is given for preventing the resonance and the noise without using the detection means of detecting vibration of a component, in which when drive frequency is within a resonance frequency range, drive current of a stepping motor is controlled to decrease drive force of the stepping motor, so that generation of the resonance and the noise is prevented (for example, referring to patent document 2).    Patent document 1: JP-A-7-298691    Patent document 2: JP-A-9-140193